1) If RHS exits before `echo red` is executed, `echo red` receives a SIGPIPE and crashes

2) Even if RHS does not exit quick enough, `echo red` writes output to the pipe, which is ignored by RHS `echo blue` (echo never reads stdin)

Why would you expect it to show?

Would you also expect "echo something < file.txt" to show the contents of file.txt?

Perhaps you are thinking of cat or some other command, because piping things to echo is such a strange and unexpected thing to do that you normally won't encounter it.